Treatment of oils with phosphorus pentoxide



Feb. 20, 1940. A, P. sAcHs TREATMENT 0F OILS WITH PHOSPHORUS PENTOXIDEFiled Feb. 4, 1958 INVENTOR /haer P .Sncf/s ATTORNEY 332/ WBWS ass'a'osgV Patented Feb. 2o, 1940 UNITED STATES TREATMENT or ons WITH rnosrnonusPENToxmE Albert P. Sachs, New York, N. Y., assignor to PetroleumConversion Corporation, Elizabeth, N. J., a corporation of DelawareApplcation'February 4, 1938, Serial No. 188,608

6 Claims.

My present invention relates to improvements in the use of phosphoruspentoxide (P205) in,

the treatment of hydrocarbons, especially in the purification of crudegasoline distillates and the recovery of values from the gases producedor employed in the cracking operations. Malishev, (vide U. S. Patent No.2,055;415), has already shown that P205 possesses catalytic activity inthe polymerization and condensation of olefnic or 10 other unsaturatedhydrocarbons, which activity has also been found to result in a refiningaction. The present invention is concerned with an improved applicationof these properties of P205 to the refining of crude gasoline distillateand the recovery of useful compounds from the gases produced or employedin the cracking reaction. In this manner the oleiinic content of thecracking or other gases is converted to liquids suitable for use asmotor fuel, while the liquid thus produced as Well as the crackedgasoline is refined.

In the cracking of hydrocarbons, especially in vapor phase, the reactionproducts are vapors at high temperature which are normally recovered toyield a certain amount of fuel oil, heavy gasoline distillate, lightgasoline distillate and` cracked gases which may be re-used in gasheat-carrier processes as the heat-carrying medium for the crackingprocess.l The heavy gasoline distillate is obtained by directcondensation, the light gasoline distillate by absorption from the gasesby subsequent stripping, and the total distillate is stabilized. In theoperation hitherto considered normal the stabilized distillate isreiined, as by use of concentrated zinc chloride solution or by certainclays. The gases, particularly the stabilizer tops, may be subjected tothermal or pressure polymerization, or otherwise disposed of. In otherilfapor phase cracking processes not employing a eat-carrying gas, theratio of gas to primary distillate is as a rule much smaller.

The use of P205 as a polymerizing or refining agent suers to a certainextent from the diiculty that the compounds which interact with or arecatalytically affected by the P205 cause the 4l P205 to agglomerate orform lumps. I overcome this difficulty by pretreating the hydrocarbon'.

liquids and the hydrocarbon gasesto'besubjected to the action of P205with partially spent P205 the acid nature of which simultaneously causes50 'not only the removal of nitrogenous and basic substances whichamongst others would otherwise undesirably diminish the catalytic effectof the P205 in the main course of the treatment but also the dehydratingnature of which removes actual water and such potential water as may bepresent in oxygenated compounds and which also would tend to coat theactive particles of P205 with a non-reactive film of phosphoric acid orother compounds resulting from the reaction of P205 with substancespresent in the material to l be treated. l

In my improved process I preferably simultaneously treat thegas and thedistillate (each of which has been suitably prepared for the treatment)with P205 preferably in one or more stages 10` whereby the gaseous olensare caused to react to some degree with olefins or aromatic compoundspresent in the liquid, and the liquid polymers formed from the gas arein the same operation added to the gasoline distillate, While the lpresence of the gas aids in the suspension` and distribution of P205throughout the fluids being treated. By conducting the operation in.stages involving different temperatures, various of the reactionsinvolved are subjected to temperature 20 and, if necessary, pressureconditions most favorable. Thus, one stage is preferably carried out atatmospheric temperatures which are conducive to ethane polymerizationand to alkylation, while the second stage is carried out at preferably25 around 400 F., which is required by other oleiins. Further stages maybe added if desired and especially if the distillate is not to beredistilled. Y

My invention will be best understood by rei'er- 30 ence to the followingdetailed description taken with the accompanying drawing illustrating aplant constituting a preferred embodiment of the invention.

`In this gure an accumulator I receives its 35 charge of raw gasolinedistillate and gas from the condensers of the cracking unit (not shown).'Ihe liquid passes through line 2 to a washing and dehydrating system 3which may consist of a tower 3a for washing with dilute caustic, a tower40 3b for washing with dilute sulfuric or phosphoric acid, and a tower3c where the washed and settled distillate is mingled with spent P205suspension from sett1ers'2l and 36 (to be more particularly describedhereinafter) to accomplish VVthe dehydration and pretreatment of thedistillate, suitable connections being provided for the admission andwithdrawal of the treating reagents and for passing the gasoline fromone tower to the other, all as indicated. The caustic solution acts toremove hydrogen sulfide, some mercaptans and any acidic substances,while the acid wash removes any nitrogen bases.l The action of thepartially spent P205 in the tower 3c is, as above pointed out, highlyimportant, since l pressor 9, passesvby line I to intermediate retherebysubstances which -consume the P205 (without producing any desiredpolymers or condensation products) are substantially removed. The drypretreated distillate passes by line 4 to P205-contact tower 5 where itis contacted with a suspension, suitably prepared, of P205 in heavykerosene or gas oil. This heavy kerosene or gas oil is preferablypretreated with partially spent P205 to remove substances which consumeor reduce the effectiveness of P205. Pump 6 receives the suitablyprepared suspension of P205 and transfers it by line 'I to tower 5 at apoint desirably above the midpoint of the liquid column therein.

Reverting to accumulator I, the gas component leaves by line 8, iscompressed by comceiver II from which any condensate is returned by lineI2 to accumulator I. The compressed gas from intermediate receiver IIpasses by line I3 to the gas washing pretreating and dehydrating systemI4 which is substantially similar to system 3 above described, with suchchanges as are necessary, so that system I4 may wash the gas with diluteNaOH solution in tower I4a, with dilute sulfuric or phosphoric acid intower I4b and with spent P205 suspension in tower I 4c. The drygaspasses from system I4 by line I5 to tower 5 at a point desirablybelow the midpoint thereof, the gas bubbling up through the distillateand P205-suspension at substantially atmospheric temperature, its actionaiding the suspension and affording the agitation/ desirable tothoroughly distribute the suspension throughout the liquid undergoingtreatment. Suitable distributor heads or other devices (not shown) maybe provided for distributing the gas in nely divided conditionthroughout the mass of liquid'in the tower 5, and baffle plates may beprovided to extend the path and; increase the time of contact of thegaswith the P205-suspension in the distillate.

The partially depleted gas leaves tower 5 by line I6, is compressed bycompressor I1, passes by line I8 to heat-exchanger I9 where it is heatf20 into settling tank 2I which is of such. diameter and height as topermit most of the suspended P205 to settle out. Pump 23 draws ofi.'concentrated P205-suspension through line 22 leading from the bottom ofthe settler-'2l and discharges it by line 24-into line Y'I in order toproduce recirculation of P205 through the tower 5. From time to time, orcontinuously, P205- suspension may be withdrawn from the circuit bymeans of valve 25 and line 26. The partially spent H05-suspensionwithdrawn by line 26 may then be transferred to either or both thepretreating and dehydrating tower-3c of the distillate washing,pretreating and dehydrating system 3, or to the pretreating anddehydrating tower I4c of the gas washing-system I4. As shown in thedrawing, it is fed to tower 3c by line 26 having therein valve 25. Asubstantially P205-free distillate overflows from settler 2l throughline 2l and passes thence to heater 28 where it is heated by indirectcontact with fluids (as, for` example, fromrthe cracking unit) to a Ivtemperaamg of preferably 30o-400 F. The heated gas from heat-exchangeri9 passes by line 29 whilethe heated distillate (which may be partlyvaporized) from heater 2B passes by pipe 30 to respective pointsadjacent the bottom of tower 3|. This column, as in the case of column5, may have gas distributing means and bailles, etc., not-shown, all ofwhich act to extend the path and increase the time of contact of the gaswith the H05-suspension in the distillate.

The cooled gas passes by line 32o to an absorber 32d where it isVstripped of its content of C4 and higher boiling constituents by means.of a suitable menstruum which may be a suitable naphtha fraction Withinthe boilingv range of the gasoline to be produced. The enriched naphthamenstruum may be returned to the evaporator 45 to be mentioned below, bypipe 32e. Pump 33 pumps a suitably prepared suspension of P205 in heavykerosene or gas oil by line 34 into tower 3|, such suspension enteringthe tower above the midpoint of the liquid column therein. The overowfrom tower 3I passes to settler 36 by line 35,- which settler is similarto settler 2I and acts to separate the P205 from the distillate. Pump 38draws off concentrated P205-suspension by line 31 in the bottomrofsettler 36 and discharges it by line 39 into"`line 34 `to bring aboutrecirculation. of P2O5-suspension through the tower 3|. From time totime or continuously, H05-suspension may be withdrawn from the circuitby means of valve 40 in line 4I and the partially spent P205-suspensiontransferred to the prtreating and dehydrating tower or towers in thesystems 3 and I4 previously mentioned, as in the case of the P205 fromsettler 2|. As shown'in the drawing, it is conveyed by line 4I to towerI4c. The substantially P205-free distillate under system pressureoveriiows from settler 36 through line 42 to heat-exchanger or heater 43where it is heated by indirect contact with hot fluids (as,for example,combustion gases or hot fluids from the cracking system, not shown) to atemperature suflicient to provide for the complete flash evaporation ofthe gasoline content of the distillate in evaporator 45 to which thedistillate is transferred from heat exchanger 43 by line 44, aided bypump 44a. The overhead distillate from evaporator 45 passes by line 46to the condenser 4Gb, thence to accumulator 46c from which the liquidcondensate is pumped by pump 46d through line 46e to heat exchanger 46j(which raises the temperature suiiiciently for the stabilizationdistillation) and thence by line 46g to stabilizer 46a. The gas fromaccumulator 46c leaves by line l16h and is conveyed by the requisitecompressor and connections not shown to absorber 32d. A naphtha fractionis produced from the stabilized gasoline leaving the stabilizerv 46a byconducting some of the stabilizer bottoms through line 4l to a naphthacolumn (not shown) wherein the stabilized gasoline is topped, the saidtops being returned to the evaporator or stabilizer while the toppednaphtha is conducted by line Ll'la for use as a menstruum inthe'absorbe'r 32d and the enriched menstruum may be returned byline 32eafter suitable heating under pressure .in heat exchanger 32fto provideheat for flash evaporation to evaporator d5. The bottoms containing allmaterials heavier than gasoline leave the evaporator 45 by line 48, andafter cooling in cooler 48a are washed with dilute alkaline solutions toremove any P205 or acidic phosphorus compounds and the washed bottomsmay be used as a cracking stock, as suspension medium for P205 or asfuel oil.

The stabilizer overhead passes by line 50 to condenser 5| and thence toaccumulator 52 from which the liquid leaves by line 53, pump 54 and line55 to be returned as reflux to stabilizer I4161i while the gas leaves byline 56 having therein the booster 51 by means of which it may be passedback to cooler 32a wherein the saturated C3 and C4 hydrocarbonscomprising largely such stabiliz' er overhead (the unsaturated Cs and C4hydro.

carbons having been used up by the P205 treatments) are therebyrecovered and added to the collecting box 32h. Such saturatedhydrocarbons may also be drawn oi from accumulator 52 by line 52acontrolled by valve 52h and may either be sold for various uses, orthermally decomposed for re-use in the present system. The gas escapingcondensation in accumulator 52 or in collecting box 32h then passesthrough the absorber 32d by means of the line 32o, so that all lean gasof the system leaves the same by way of the absorber.

An important advantage of my invention is that by properly operating thesystem a motor fuel may be produced which is water white, colorstableand gum-free. A further advantage is that yields are considerablyincreased as the effect of the P205 is to convert the gaseousunsaturates into motor fuel and because of the polymerization of thebutenes to permit additional amounts of butane and saturated gases to beincorporated in the stabilized gasoline. Furthermore. the effect of theimproved process is to increase the octane number of the distillateconsiderably, due probably to the production of polymers and condensedcompounds of a cyclic or alkylated cyclic nature which are known to havehigh anti-knock values. A still further advantage is that the cracking,refining and polymerization and the utilization of the liquid andgaseous products of cracking are made one continuous process.

It will be understood, however, that various changes may be made in thedescribed process without departing from the spirit of the invention orthe scopeof the appended claims.

I claim:

l. In the treatment of low boiling hydrocar' bons with P205 for thepurpose of purifying said hydrocarbons and utilizing the oleflniccompounds therein, the steps which consist in preparing saidhydrocarbons for said treatment by removing therefrom substances solublein dilute acid, then drying said hydrocarbons by contact therewith ofP205 of not greater impurity than that which has been previously used inthe main purifying treatment infra, and which is effective to removepotential water forming compounds detrimental to the action of therelatively fresh P205 in said treatment infra, passing a liquid streamof the so pretreated hydrocarbon to the lower'part of a-previouslyformed column thereof, adding a suspension in hydrocarbon liquid ofrelatively fresh P205 to the upper part of said column, decanting fromadjacent the top of said column a stream of said hydrocarbon laden withP205, slowing up the flow of such stream suiciently to cause said addedP205 to settle, recovering in concentrated form said P205 in suspensionthus settled out, and recovering said P205 treated hydrocarbons` 2.'I'he process of simultaneously treating crude gasoline distillate andhydrocarbon gases containing oleiins, consisting in removing substancessoluble in dilute acid from both distillate and gas, drying bothdistillate and gas and treating same with P205 of not greater impuritythan that which has been previously used in the main purifying treatmentinfra, and which is effective to remove potential water formingcompounds detrimental to the action of the fresh P205 in said treatmentinfra, suspending relatively fresh P205 in a stream of said distillateand passing said gas therethrough whereby both distillate and gas aresimultaneously treated by said P205, the liquid polymers formed fromsaid gas being added to said liquid hydrocarbon, and the suspension ofthe P205 in the distillate aided by the iiowof said gas, thereaftercausing Vthe P205 to settle, passing the treated gaseous stream to anabsorber for recovery of light ends therein and subjecting the treateddistillate to vaporization to effect removal therefrom of compoundsdistilling above the desired gasoline end point.

3. 'I'he process of simultaneously treating crude in a stream of saiddistillate in a first treating zone and passing said gas therethroughwhereby both distillate and gas are simultaneously treated by said P205,the liquid polymers formed. from said gas added to said liquidhydrocarbon, and the suspension of the P205 in the distillate aided bythe flow of said gas, thereafter causing the P205 to settle, removingthe distillate from said first treating zone, heating same, and passingthe heated distillate into a second zone of treatment having a highertemperature than said first zone. wherein a fresh suspension of P205 isadded, removing the gas from the first zone of treatment, compressingand heating same, adding the heat'm ed gas to said second zone oftreatment, passing the thus treated gas to an absorber to recover valuestherefrom, separating the thus treated' distillate from said P205 addedin said second zone of treatment, 4and distilling same to recover a newdistillate of desired end boiling point.

4. In the treatment of low boiling hydrocarbons with P205 in which saidhydrocarbons are first treated to remove acid and alkali solubleimpurities if present, the method which consists I.

in treating the thus purified hydrocarbons with P205 in stages involvinga preliminary stage and an intensive stage and wherein relatively pureP205 is used in the intensive stage and the spent P205 therefrom is usedin the preliminary stage to remove from said treated hydrocarbon thepotential water forming compounds so as to prevent agglomeration of theP205 in the intensive stage,l and carrying out said intensive stage bythe simple mingling of the hydrocarbon and the P205. Y

Y5. In the method of treating low boiling liquid hydrocarbons with P205for the purpose .of purifying same and utilizing the olenic compoundstherein, the steps which consist in first removing fil therefromsubstances soluble in dilute acid, subjecting the so treated hydrocarbonto the action of partially spent P205 to remove free moisture andcompounds producing moisture upon subsequent reaction with P205, passinga liquid stream of so pretreated hydrocarbon to the lower part oi' apreviously formed column thereof, adding a suspension of relativelyfresh P205 to the upper part of said column, decanting from adjacent thetop of said column a stream of said hydrocarbon laden with P205, slowingup vthe flow of said stream suiciently to cause said added PzOs tosettle, recovering in concentrated form said P205- suspension thussettled out, recovering said P205 treated hydrocarbons and returning thepartially spent P205 so obtained to contact with the hydrocarbonsundergoing treatment for removal o! moisture.

6. The process of simultaneously treating crude gasoline distillate andhydrocarbon gases ciontaining olens, consisting in removing substancessoluble in dilute acid from both distillate and gas, drying bothdistillate and gas. and treating same with P205 of not greater impuritythan that which has been previously used in the main purifying treatmentinfra, and which is effective to remove potential water formingcompounds detrimental to the action of the fresh P205 in said treatmentinfra, suspending relatively fresh P205 in a stream of said distillateand passing said gas therethrough whereby both distillate and gas aresimultaneously treated by said P505, th'e liquid polymers formed fromsaid gas being added to said liquid hydrocarbon, and the suspension ofthe P205 in the distillate aided by the ow of said gas, thereaftercausing the P205 to settle, passing the treated. gaseous stream to anabsorber for recovery of light ends therein and subjecting the treateddistillate to vaporization to effect removal therefrom of compoundsdistilling above the desired gasoline end point, utilizing a distillatefrom said vaporization step as the absorber menstruum and returning tothe'zone of vaporization the enriched absorber menstruum.

ALBERT P. SACHS.

- Y CERTIFICATE OF CORRECTION. Patent No. 42,191,0lt5.. February 20,19110.

` l ALBERT P. SACHS.

It is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction as follows: Page l,second column, line 2h, for "ethane" read ethene; and that the saidLetters Patent should be read with this correction therein that the samemay oonform to the record of the oase in the Patent Office.`

Signed and sealed this 9th day of April, A. D. 19LLO.

Henry Van Arsdale,

(Seal) Acting Commissioner of' Patents.

